Preparation and properties of high viscosity and elasticity asphalt by styrene–butadiene–styrene/polyurethane prepolymer composite modification

The porous asphalt pavements is often used in important occasion for its special properties and performance which can be to a great extent attributed to the binder—high viscosity and elasticity asphalt (HVEA). To prepare high demanding binder for porous asphalt pavements, the polyurethane prepolymer (PUP) and styrene–butadiene–styrene (SBS) were used to modify the matrix asphalt compositely. First, based on a series of physical tests, the effects of binder composition on performance of SBS/PUP HVEA binder (SBS/PUP-HVEA) were investigated. Then the Fourier transform infrared (FTIR) test was conducted to investigate the reaction mechanism of SBS/PUP-HVEA binder. Last, the fluorescence microscopy, stability tests, multiple stress creep recovery test, and differential scanning calorimetry test were carried out to evaluate and compare the phase structure, storage, high-temperature performance, thermostability characteristics of several HVEA binders. It is found that the composite modification of SBS and PUP can produce high quality binder which possesses high viscosity and high elasticity. And the composition of SBS/PUP-HVEA were recommended as follows: Shell-70# can be chosen as matrix asphalt, the contents of SBS modifier (SBS1301:SBS4303 = 1:2), H2122A PUP, chain extender M-OEA, and crosslinker sulfur were suggested 4%, 5%, 0.5%, and 1‰, respectively. The new functional groups observed in FTIR confirmed the existence of physical and chemical reactions in the modification process, which were beneficial to improve the high temperature performance and storage stability of the binder. SBS/PUP-HVEA had good phase structure, storage stability, high temperature performance, and thermostability compared to other HVEA binders. This study demonstrated that the SBS/PUP compositely modified asphalt possessed high viscosity and high elasticity, which can be used in the porous asphalt mixture and other highly demanding working environment as well.     

Research for SEBS/PPA compound‐modified asphalt

In this study, polyphosphoric acid (PPA) was used to modify styrene–ethylene/butylene–styrene (SEBS)‐modified asphalt further and decrease the SEBS content in asphalt. Different structural analysis methods including morphology observation, infrared spectroscopy, thermal analysis were used to investigate the structural characteristics of asphalt modified by SEBS or PPA before and after short‐ or long‐term thermal ageing. The study shows the suitable addition of PPA can improve the major physical and rheological properties of SEBS‐modified (SM) asphalt and the improved properties became more obvious with further ageing. 0.8 wt % PPA can replace 2 wt % SEBS in the modification. Morphology observation showed PPA increased the incompatibility between SEBS and asphalt. Thermal analysis showed PPA changed the energy consumption and mass loss of SM asphalt greatly at elevated temperatures and led to the more complex structural characteristics. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46085.     

Internal structure of bitumen/polymer/wax ternary mixtures for warm mix asphalts

Polymer modified asphalts (PMA) and warm mix asphalts (WMA) are technologies widely adopted in the paving industry. The first one is well established, while the second one is relatively new, but rapidly growing since it guarantees economic and environmental advantages. Until now PMA and WMA have been used disjointedly, but it would be useful to combine them to keep the advantages of both. One of the adopted solutions to obtain a warm effect is the addition of waxes to the asphaltic binder. Therefore, a “warm mix polymer modified asphalt” may be potentially obtained with a ternary asphalt/polymer/wax system. However, the final warm effect and performances of the binder will depend on the interactions between the three components. A preliminary investigation was done by mixing asphalt, styrene‐butadiene‐styrene block copolymer and a wax chosen among the following three categories: paraffinic, partially oxidized and maleic anhydride functionalized. The morphological and calorimetric analyses and solubility tests allowed identifying different behaviors depending on the wax type, which may preferentially interact either with the asphalt or with the polymer, thus influencing the whole binder structure. With regard to the ternary mixes, it was found that: (i) the paraffinic wax preferentially resides in the polymer‐rich phase, and slightly enhances the asphalt‐polymer compatibility; (ii) the partially oxidized wax prefers the asphaltene‐rich phase and reduces the compatibility; (iii) it is not clear where the functionalized wax is located, but it has a considerable compatibilizing effect and strongly alters the colloidal equilibrium of the asphalt‐polymer blend. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Fundamental characterization of SBS‐modified asphalt mixed with sulfur

The purpose of this study was to characterize the mechanical behavior of asphalt modified by styrene–butadiene–styrene (SBS) and sulfur. Viscosity, microscopy, and rheological tests were conducted to understand the engineering properties of the polymer‐modified asphalt (PMA). Without the addition of sulfur, the polymer‐modified asphalt was microheterogeneous and was made up of two distinct finely interlocked phases, especially at high SBS concentrations. After the addition of sulfur, the PMA was observed to have smaller asphalt domains and a fairly homogeneous dispersion of the asphalt in the SBS matrix. The compatibility between polymer and asphalt produced an elastic network into the asphalt. The addition of sulfur resulted in an excellent elastic system and substantially increased the rheological properties of the PMA. Because of the colloidal nature of asphalt cements, their engineering properties were greatly improved because of the reinforcement of the SBS polymer and the physical‐chemical interaction between SBS and asphalt. The difference in the softening point between the top and bottom layers decreased significantly, and elastic recovery increased when was sulfur was present. A viscoelastic model was examined and shown to be appropriate for predicting the rheological properties ofthe asphalt–SBS blend mixed with sulfur. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2817–2825, 2007     

Use of rheological compatibility criteria to study SBS modified asphalts

Polymer‐modified asphalts (PMAs) were prepared using Bachaquero asphalt and styrene–butadiene–styrene (SBS) type copolymers. Their rheological behavior was compared to that of unmodified asphalt and of a compatible commercial PMA. Materials were submitted to frequency sweeps between 10^?1 and 10² rad/s from 0 to 50°C. Storage stability tests were performed for 72 h at 160°C. Ring and ball softening points from the top and the bottom of the blends were compared and were used along with fluorescence microscopy to evaluate stability. Samples prepared with styrene–ethylene–butylene–styrene (SEBS) showed improved compatibility and stability as compared with SBS‐modified asphalts, probably because of a higher stability to thermal degradation from the absence of double bonds. An additional improvement in stability and compatibility was observed for SEBS functionalized with maleic anhydride (SEBS‐g‐MAH)–modified blends. Better compatibility, however, did not improve rheological behavior at low temperatures. The systems studied are so complex from a chemical point of view that the rheological criteria normally used to predict compatibility of polyblends did not give enough information regarding the compatibility of the modified asphalts. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1772–1782, 2003     

The research for high‐elastic modified asphalt

High‐elastic modified (HEM) asphalt was prepared by the addition of styrene‐butadiene‐styrene (SBS), plasticizer, and crosslinker to base asphalt. The effect and proportion of each modifier in asphalt were studied using physical and rheological tests. It was found that SBS determined the high‐temperature performance of HEM asphalt mainly. Plasticizer (dioctyl phthalate) is very helpful in improving the low‐temperature flexibility and elastic recovery. Crosslinker (sulfur) is necessary in maintaining high‐temperature stability. In this study, Fourier transform infrared, hydrogen nuclear magnetic resonance analysis, and microscopy observation were used to investigate the structural characteristics of modified asphalts further before and after ageing. The research showed the structural characteristics of modified asphalt were influenced evidently by ageing. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42132.     

石墨烯/聚乙烯复合改性沥青胶结料的流变性能研究

为提高沥青胶结料的综合路用性能,尤其是高温性能,本文采用高速剪切机将质优价廉的聚乙烯(PE)与石墨烯纳米片(GNPs)复合制备新型沥青胶结料,同时使用温度扫描(TeS)、多重应力蠕变恢复(MSCR)、线性振幅扫描(LAS)和傅里叶变换红外光谱(FTIR)研究了石墨烯/聚乙烯复合改性沥青胶结料的流变性能和作用机理。结果表明:GNPs和PE能够协同改善沥青胶结料的高温性能,提高路面的高温车辙抗性;预混的PE/GNPs母粒具有良好的中温疲劳和低温开裂抗性。同时复合改性沥青的FTIR光谱中未出现新的吸收峰,表明石墨烯和聚乙烯在沥青基体中以物理改性为主。     

Comparative study of the effect of sulfur on the morphology and rheological properties of SB‐ and SBS‐modified asphalt

The modification of asphalt with styrene‐ butadiene block copolymers and sulfur was studied to elucidate the effect of the molecular characteristics of the polymer, polymer content, and sulfur/polymer ratio on the physical properties of modified asphalts. Two types of styrene‐butadiene copolymers were used (SB and SBS), which differed considerably in terms of their chain architecture, average molecular weights, and size and distribution of their polybutadiene and polystyrene blocks, as shown by gel permeation chromatography, infrared spectroscopy, nuclear magnetic resonance, and differential scanning calorimetry. Sulfur/polymer/asphalt blends were prepared by a hot mixing process and characterized by conventional tests, fluorescence microscopy, and rheology. The results revealed that the morphology of the blends is strongly dependent on polymer concentration and sulfur/polymer ratio. In‐depth rheological characterization showed that the thermomechanical properties changed considerably upon addition of small amounts of sulfur. Collectively, these results suggest that sulfur increases the compatibility between polymer and asphalt by crosslinking polymer chains. Interestingly, the rheological behavior of blends prepared with a combination of SB and sulfur was similar to that exhibited by blends prepared with SBS either in the presence or absence of sulfur. This is explained by assuming that the addition of small amounts of sulfur to SB‐modified asphalt facilitates the formation of an elastomeric network that resembles the one found in SBS‐modified asphalt, effectively contributing to asphalt reinforcement. Nonetheless, the exact dosage of sulfur must be carefully controlled to prevent gel formation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Physical and rheological properties of crumb rubber/styrene–butadiene–styrene compound modified asphalts

In order to improve the storage stability and tenacity of crumb rubber modified (CRM) asphalt, CRM compound modified asphalt was prepared by the addition of styrene–butadiene–styrene (SBS) and sulfur. The addition of SBS improved the tenacity of CRM asphalt, due to the formation of a dense polymer network. The storage stability of crumb rubber (CR)/SBS‐modified (CRSM) asphalt was improved by the addition of sulfur. The rheological tests confirmed the effect of SBS and sulfur on the physical properties of CRM asphalt to some extent and showed the susceptibility of CR/SBS/sulfur‐modified (CRSSM) asphalt to dynamic shearing. The morphology observation showed the compatibility of CRSM asphalt was improved greatly by vulcanization. POLYM. COMPOS., 38:1918–1927, 2017. © 2015 Society of Plastics Engineers     

Effects of polyphosphoric acid (PPA), styrene-butadiene-styrene (SBS), or rock asphalt on the performance of desulfurized rubber modified asphalt

To improve the performance of desulfurized rubber modified asphalt (DRMA), especially its high-temperature performance, three modifiers (including polyphosphoric acid [PPA], styrene-butadiene-styrene [SBS], and rock asphalt) were selected to modify DRMA respectively. The conventional performance, rheological properties, chemical composition, and thermal decomposition were characterized to analyze the performance and modification mechanism of DRMA and its composites. Test results show that, the addition of PPA, SBS, and rock asphalt can all improve the high temperature of DRMA, among which the desulfurized rubber/rock asphalt compound modified asphalt (DRMA-ROCK) has the best high-temperature performance; however, its construction workability, storage stability, and low-temperature performance are poor. In contrast, desulfurized rubber/PPA compound modified asphalt (DRMA-PPA) not only has better high-temperature performance, but also has excellent low-temperature performance, storage stability, and fatigue performance. Fourier infrared spectroscopy (FTIR) test confirms that the modification process of DRMA by these modifiers is chemical modification, and the characteristic peak indexes obtained from FTIR also prove that DRMA-ROCK has better high-temperature performance but poor construction workability from the microscopic point of view. Furthermore, thermogravimetric analysis-differential scanning calorimetry test shows that the addition of rock asphalt improves the thermal stability of DRMA, while PPA and SBS decrease its thermal stability. From the above results, it can be concluded that DRMA-PPA has excellent comprehensive properties.     

Memory functions in polymer modified asphalts

The viscoelastic nonlinear behavior of several base and polymer modified asphalts (PMA) has been studied in step‐strain experiments. The polymers were poly(styrene‐b‐butadiene‐b‐styrene), poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene), poly(ethylene‐r‐vinylacetate) copolymers, and a linear low density poly(ethylene), which were chosen as representatives of the main categories of asphalt modifiers. Because of the complexity of the morphological structure of these materials, the relaxation modulus has only partial and qualitative similarities with that of melt or high concentrated solutions of entangled polymeric liquids. No time strain separability can be applied, and the relaxation experiments are conveniently described by means of the memory functions. These have been calculated both via a parametric fitting procedure and by interpolation algorithms. Results are presented, and a correlation between the PMA structure and the corresponding memory function is proposed for the investigated materials. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2330–2340, 2007     

Preparation and properties of high viscosity modified asphalt

High viscosity modified (HVM) asphalt was prepared by the addition of styrene–butadiene–styrene (SBS), plasticizer, crosslinker. The effect and proportion of each modifier in the preparation of HVM asphalt were studied. SBS was the major modifier and determined the basic properties of HVM asphalt. Plasticizer (furfural exact oil) and crosslinker (sulfur) as additional modifiers were necessary in improving the workability, stability, and aging resistance of modifier. The effect of aging and additional modifiers on the structure and rheological behavior of SBS modified (SM) asphalt was displayed by adopting various rheological tests. Plasticizer declined the rutting resistance of SM asphalt and increased the viscous behavior of SM asphalt after aging. The use of crosslinker led to the formation of polymer network and improved the aging resistance of SM asphalt. The morphology observation shows crosslinker led to the formation of polymer network and improved the compatibility between SBS and asphalt. Plasticizer prompted the swelling and dispersion of SBS in asphalt and improved the effect of crosslinker further. Aging destroyed the polymer phase seriously and there was still residual polymer phase in asphalt. POLYM. COMPOS., 38:936–946, 2017. © 2015 Society of Plastics Engineers     

Laboratory investigation of the properties of asphalt modified with epoxy resin

Epoxy asphalts were prepared by mixing styrene–butadiene–styrene (SBS) modified asphalt with epoxy resin. The curing process and morphology of epoxy asphalts were characterized by infrared spectroscopy and fluorescent microscope, respectively. The effects of epoxy resin contents, ratio of curing agent to epoxy resin and curing temperature on properties of epoxy asphalt were investigated. Results indicated that epoxy resin and epoxy asphalt showed similar curing efficiency. Epoxy asphalts can be cured at 120 or 60°C and its viscosity at 120°C can meet the demands of asphalt mixture mixing and paving. The chemical reaction of epoxy resin in epoxy asphalt is slow and reaction occurs not only with the curing agent but also carboxylic acid in epoxy asphalt. The microstructure of epoxy asphalt transforms from the dispersed structure to networks structure with epoxy resin content increasing and phase transition starts when 30 wt % epoxy resin present in asphalt. The softening point and tensile strength of epoxy asphalt increased with epoxy resin contents increasing. The softening point and tensile strength of epoxy asphalt were markedly improved when epoxy resin content was more than 30 wt %, which is attributed to formation of continuous structure of epoxy resin. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Study on percolation phenomena and mechanism of enhanced asphalt by polymers

Abstract

The properties of asphalt modified by styrene–butadiene–styrene, polyvinyl acetate and waste crumb rubber separately in a wide range of polymer loadings were studied in this paper. In analysing the relationship between polymer loading and modified asphalt properties, we found that the ductility of polymer modified asphalt measured at 5°C exhibited a percolation phenomenon, that is, as the loading of polymer exceeded a critical value, the ductility of modified asphalt changed abruptly. Furthermore, a percolation threshold differential existed. A rubber processing analyser, an optical microscope and a fluorescence microscope were used to characterise the microstructure of polymer modified asphalt and validate the occurrence of a polymer network in modified asphalt as a function of polymer loading. The percolation phenomenon of polymer modified asphalt was found to be associated with the polymer network in modified asphalt and can be well explained by the percolation mechanism of rubber toughened plastics.     

SBS对沥青性能的影响

通过测试软化点、针入度和延度对SBS改性沥青的性能进行表征.结果表明:使用线型或星型SBS作为沥青改性剂可以显著提高沥青性能.当硫黄稳定剂质量分数为0.2％,SBS质量分数为4％时,改性沥青的软化点、针入度和延度趋于稳定.此外,相较于线型SBS改性,星型SBS改性沥青的软化点稍高,针入度和延度相对更小.     

阳离子型丁苯胶乳的合成及其改性乳化沥青的性能

以胜利炼油厂生产的90#重胶沥青为基质沥青,使用丁苯胶乳（SBR）为改性剂,分别筛选了三种不同的乳化剂及稳定剂制备阳离子改性乳化沥青,考查了pH值对乳化沥青稳定性的影响,探讨了SBR的用量对沥青性能的影响。结果表明,在乳液pH值为3～4、沥青温度120℃、水温70℃,乳化剂用量为1.45%（R2∶R3=6∶4）,丁苯胶乳为4%（干基）,稳定剂W3为0.3%条件下制备的改性乳化沥青达到交通部规定的质量要求,并具有优异的低温性能。     

Recycled polycarbonate/acrylonitrile–butadiene–styrene reinforced and toughened through chemical compatibilization

To improve the utilization efficiency of recycled polycarbonate/acrylonitrile–butadiene–styrene (R-PC/ABS), we studied the mechanical, morphological, and rheological properties of R-PC/ABS with styrene–butadiene–glycidyl methacrylate (SBG), which was used to reinforce and toughen the R-PC/ABS through chemical compatibilization. Fourier transform infrared spectroscopy demonstrated that carboxyl and hydroxyl groups in R-PC/ABS reacted with epoxy groups in SBG to produce ester and ether groups. The results of scanning electron microscopy show that the domain sizes of the ABS particles decreased when the SBG content was 6 wt %; this demonstrated that the compatibility of the polycarbonate (PC) and ABS was improved after the addition of SBG. The results of the loss modulus of dynamic mechanical analysis were consistent with the morphological results, which reflected a better compatibility of PC and ABS in the modified samples. The introduction of SBG increased the molecular weight and entanglements; this improved the viscosity and storage modulus in the modified samples, as demonstrated by the rheological results. Furthermore, the mechanical properties were obviously enhanced, especially the impact strength, when the SBG content was 6 wt %; this was ascribed to the chemical reactions and improved compatibility after melt extrusion with SBG. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47537.     

Combustion properties of asphalt binder containing flame retardant

Combustion characteristics of asphalt binder containing flame retardant (magnesium hydroxide, MH) were investigated using thermogravimetry and Fourier transform infrared spectrometer, and multistage combustion model of asphalt binder was developed. The results indicate that the combustion processes of asphalt binder and MH‐modified asphalt binder both include three main sequential stages. But with the MH concentration increase, the release amount of flammable volatiles is reduced, and the asphalt binder ignition time is delayed. Asphalt binder thermal stability is improved by incorporation of MH. At the same MH concentration, the kinetics parameters increase from the first to third stage. But in each stage, the kinetics parameters exhibit an increase trend in the first stage as the MH content increases, but in the second and third stages, the kinetics parameters show a trend of first increase and then decrease. Furthermore, the parameters reach the maximum at the concentration of around 20% by weight. This concentration may be appropriate for flame‐retarding asphalt binder. It is concluded that MH may be used as a new kind of environment‐friendly flame retardant for asphalt binder, and the developed thermal analysis kinetics model can be employed to evaluate the combustion characteristics of asphalt binder. Copyright © 2011 John Wiley & Sons, Ltd.     

基于正交试验的多聚磷酸复配SBS改性沥青粘弹性研究

为了探究多聚磷酸(PPA)复配SBS改性沥青组成材料对其粘弹性的影响,本文以SK90#基质沥青、SBS改性剂、抽出油、稳定剂、PPA、邻苯二甲酸二丁酯(DBP)为原材料,在正交试验设计的基础上,用高速剪切机制备了PPA复配SBS改性沥青,利用动态剪切流变仪分析了其粘弹特性.结果表明:(1)随着温度的升高,PPA复配SBS改性沥青的抗车辙因子随之降低、弹性减弱、抗永久变形能力降低,而其相位角增大、粘性增强、不可恢复变形能力提高.(2)当多聚磷酸的掺量为0.5％,复配改性沥青的其他组分选择最大掺量(均为3号水平)时提高了其粘弹性能,达到最优流变性能.(3)当PPA掺量为0.5％,SBS掺量为4％,抽出油掺量为2％,DBP为2％时,其复配改性沥青的性能最佳.